AUTOLOGOUS CHONDROCYTE IMPLANTATION (ACI) FOR TREATMENT OF FOCAL CHONDRAL DEFECTS OF THE KNEE – A CLINICAL, ARTHROSCOPIC, MRI AND HISTOLOGIC EVALUATION AT TWO YEARS

Abstract

Introduction and Aims: To determine the efficacy of autologous chondrocyte implantation (ACI) in treating focal chondral defects of the knee, we reviewed the two-year treatment outcome of ACI in 53 patients through clinical evaluation, MRI, second-look arthroscopy and core biopsies obtained.

Method: From November 2000 to December 2003, 54 consecutive knees with 72 focal chondral defects (grade III or IV by modified Outerbridge) were treated with ACI using the Peterson periosteal patch technique. In this method, an initial arthroscopy was carried out to confirm the suitability for repair and when appropriate, cells were harvested either from the margins of the lesion, the intercondylar notch or both. The harvested cells were proliferated in vitro. Three to four weeks later, the cells were implanted in the defect with a medial or lateral parapatellar arthrotomy approach. A standardised post-operative rehabilitation protocol was carried out depending on the site of the lesion or lesions.

Results: Improvement in mean subjective score from pre-operative (37.6) to 12 months (56.4) and 24 (60.1) months post-ACI were observed. Knee function levels also improved (86% ICRS III/IV to 66.6% I/II) from pre-operative period to 24 months post-implantation. Objective IKDC score of A or B were observed in 88% pre-operatively. This decreased to 67.9% at three months before improving to 92.5% at 12 months and 94.4% at 24 months post-implantation. Transient deterioration in all these clinical scores was observed at three months before progressive improvement became evident. MRI studies demonstrated 75.3% with at least 50% defect fill, 46.3% with near normal signal, 68.1% with mild/no effusion and also 66.7% with mild/no underlying bone marrow edema at three months. These values improved to 94.2%, 86.9%, 91.3% and 88.4% respectively at 12 months. At 24 months, further improvement to 97%, 97%, 95.6% and 92.6% respectively were observed. Second-look arthroscopy carried out in 22 knees (32 lesions) demonstrated all grafts to be normal / nearly normal based on the International Cartilage Repair Society (ICRS) visual repair assessment while core biopsies from 20 lesions demonstrated 13 (65%) grafts to have hyaline / hyaline-like tissue.

Conclusion: Improvement in clinical and MRI findings obtained from second-look arthroscopy and core biopsies evaluated indicate that, at 24 months post-ACI, the resurfaced focal chondral defects of the knee remained intact and continued to function well.